1. Field of the Invention
The present invention relates to an image-forming apparatus, such as an electrostatic photographic copying machine and printer, with a bookbinding function to multi-functionalize said image-forming apparatus.
2. Description of the Prior Art
In a conventional bookbinding method illustrated in FIGS. 29, 30(A) and 30(B), a plurality of papers (e) are put in a binder (d) provided with an electric heating member (c) with an adhesive (b) on the side of an inner surface of a back cover (a) thereof. A binder-charged portion (h) is provided with electrodes (f), (f) for electrifying said electric heating member (c), and an electric current is applied to the electric heating member (c) through said electrodes (f), (f) to melt said adhesive (b), whereby said plurality of papers (e) is adhered to said side of the inner surface of said back cover (a) of the binder (d).
In addition, eyelet-like electric current-receiving terminals (i), (i) pass through the electric heating member (c) and the back cover (a) at both end portions of the electric heating member (c) to be exposed on the side of an outer surface of the back cover (a).
In another conventional bookbinding method, an adhesive (b) is merely applied to the side of an inner surface of a back cover (a) of a binder (d) and said adhesive (b) is heated and melted by means of a heat source (j) provided in a binder-charged portion (h) to adhere a plurality of papers (e) to the side of said inner surface of said back cover (a) of said binder (d), as shown in FIGS. 31(A) and 31(B).
However, the above described bookbinding devices have been used exclusively for bookbinding, so that the above described bookbinding devices have been supplied separately from image-forming apparatus, such as electrostatic photographic copying machines and printers. With these separate devices, it is necessary to perform a series of operations in which images are formed by copying and the like and then the papers are separately bound. The use of such separate apparatus has become remarkably uneconomical as a whole, and large installation spaces have been required.
In addition, in the bookbinding devices o this type, it has been remarkably important, when the binder-charged portion (h) is charged, that the back cover (a) of the binder (d) be brought into close contact with the heat source (j), or that the electric current-receiving terminals (i), (i) of the electric heating member (c) be brought into close contact with the electrodes (f), (f). However, it has been a problem that foreign matter, such as dust and paper powder, has entered into the binder-charged portion through a binder-inserting hole, and has become stuck to surfaces where the heat source (j) or the electrodes (f), (f) are engaged with the binder. This has led to the back cover (a) of the binder being brought into poor contact with the heat source (j) and the electric current-receiving terminals (i), (i) being brought into poor contact with the electrodes (f), (f), and thus to a non-uniform and insufficient heating of the adhesive (b).
In particular, the above described tendency of foreign matter to enter into the binder-charged portion has been especially notable in binders in which the binder-inserting hole is formed in an upper portion to charge the binder from above.
On the other hand, in the binder (d) provided with the electric heating member (c) with the adhesive (b) on the side of the inner surface of the back cover (a), the electric heating member (c) is different in length, and thus resistance, for different sized papers. Thus, when a constant electric current is provided for an appointed time, disadvantages have occurred in that the total calorific volume of the electric heating member (c) per unit length for a unit time is greatly changed for different sized papers. For example, with a binder of middle size as the standard, the smaller the binder size is, the more excessive the calorific value is, and the larger the binder size is, the more wanting the calorific value is. Therefore, the desired bookbinding can not be achieved.